Problem: Let $a$ and $b$ be complex numbers: $\begin{align*} a &= -3 - 4i \\ b &= 4 + 5i \end{align*}$ What is $a-b$ ? 1 2 3 4 5 6 7 8 9 10 11 \llap{-}2 \llap{-}3 \llap{-}4 \llap{-}5 \llap{-}6 \llap{-}7 \llap{-}8 \llap{-}9 \llap{-}10 \llap{-}11 1 2 3 4 5 6 7 8 9 10 11 \llap{-}2 \llap{-}3 \llap{-}4 \llap{-}5 \llap{-}6 \llap{-}7 \llap{-}8 \llap{-}9 \llap{-}10 \llap{-}11 Re Im a b
Explanation: Subtract the real and imaginary components separately. $a - b = (-3 - 4) + (-4 - 5)i$ $\hphantom{a - b} = -7 - 9i$